Method and apparatus for generating auto gain control signal having information storing feature

Abstract

The present invention discloses a device and method for generating an auto gain control signal. When a gain of an input signal is very different from a wanted gain, an increase of an integral value is prevented by repeatedly resetting an integrator. Especially, the device can sensitively respond to a fast moving substance on a channel, by reducing a repeated reset period of the integrator. At the same time, it is possible to minimize reduction of the performance of a receiver due to a residual jitter generated by the shortened period. As a result, the receiver has an improved performance in regard to the gain variations of the whole channels.

What is claimed is:  
     
       1. A device for generating an auto gain control signal, comprising: 
       an A/D converter for converting an inputted analog signal into a digital signal;  
       an absolute value calculator for calculating an absolute value of the digital signal inputted from the A/D converter;  
       an integrator for subtracting a predetermined average from the absolute value, adding the resultant value to a preceding integral value, and being reset at predetermined intervals;  
       a frequency divider for calculating an average of the output from the integrator, and removing a predetermined number of low bits proportional to the integral time;  
       an up/down signal generator for generating an up/down signal for controlling a gain according to the output from the frequency divider; and  
       a gain converter for storing information used to control the gain from the initial stage of the system operation, adding the information to the information of the up/down signal from the up/down signal generator, and controlling a gain of the analog signal inputted to the A/D converter.  
     
     
       2. The device according to  claim 1 , wherein the integrator comprises: 
       a subtracter for subtracting a predetermined average from the absolute value;  
       an adder for adding the output from the subtracter to a preceding integral value;  
       a first storing unit repeatedly reset according to a repeated reset signal, for storing the output from the adder, and feeding back the stored value to the adder as the preceding integral value; and  
       a second storing unit enabled according to the repeated reset signal, for storing a value from the adder just before the first storing unit is reset.  
     
     
       3. The device according to  claim 1 , wherein the up/down signal generator converts the output from the frequency divider into sign and magnitude information, decides a gain control direction according to the sign information, and decides a gain control amount according to the magnitude information. 
     
     
       4. The device according to  claim 3 , wherein the up/down signal generator decides the gain control amount by squaring the magnitude information. 
     
     
       5. A device for generating an auto gain control signal, comprising: 
       an A/D converter for converting an inputted analog signal into a digital signal;  
       an absolute value calculator for calculating an absolute value of the digital signal inputted from the A/D converter;  
       an integrator for subtracting a predetermined average from the absolute value, adding the resultant value to a preceding integral value, and being reset at predetermined intervals;  
       a frequency divider for calculating an average of the output from the integrator, and removing a predetermined number of low bits proportional to the integral time;  
       a conversion and square unit for obtaining sign and magnitude of the signal from the frequency divider, and squaring the magnitude;  
       an up/down signal generator for generating an up/down signal for controlling a gain according to the sign and squared magnitude information from the conversion and square unit; and  
       a gain converter for storing information used to control the gain from the initial stage of the system operation, adding the information to the information of the up/down signal from the up/down signal generator, and controlling a gain of the analog signal inputted to the A/D converter.  
     
     
       6. The device according to  claim 5 , wherein the integrator comprises: 
       a subtracter for subtracting a predetermined average from the absolute value;  
       an adder for adding the output from the subtracter to a preceding integral value;  
       a first storing unit repeatedly reset according to a repeated reset signal, for storing the output from the adder, and feeding back the stored value to the adder; and  
       a second storing unit enabled according to the repeated reset signal, for storing a value from the adder just before the first storing unit is reset.  
     
     
       7. The device according to  claim 5 , wherein the period of the repeated reset signal inputted to the integrator is shortened. 
     
     
       8. The device according to  claim 5 , wherein the up/down signal generator decides a gain control direction according to the sign information from the conversion and square unit, and decides a gain control amount according to the squared magnitude information. 
     
     
       9. An integrator for a device for generating an auto gain control signal, 
       a subtracter for subtracting a predetermined average from an absolute value of an inputted digital signal;  
       an adder for adding the output from the subtracter to a preceding integral value;  
       a first storing unit repeatedly reset according to a repeated reset signal, for storing the output from the adder, and feeding back the stored value to the adder as the preceding integral value; and  
       a second storing unit enabled according to the repeated reset signal, for storing a value from the adder just before the first storing unit is reset.  
     
     
       10. A method for generating an auto gain control signal, comprising the steps of: 
       (a) converting an inputted analog signal into a digital signal;  
       (b) calculating an absolute value of the output of step (a), subtracting a predetermined average from the absolute value, and adding the resultant value to a preceding integral value after resetting a buffer;  
       (c) removing a predetermined number of low bits proportional to an integral time;  
       (d) generating an up/down signal for controlling a gain according to the output of step (c); and  
       (e) storing information used to control the gain from the initial stage of the system operation, adding the information to the information of the up/down signal from step (d), and controlling a gain of the analog signal inputted to step (a).  
     
     
       11. The method according to  claim 10 , wherein step (b) comprises the steps of: 
       calculating an absolute value of the inputted digital signal;  
       subtracting a predetermined average from the absolute value;  
       adding the output from the subtracting step to a preceding integral value;  
       repeatedly resetting according to a repeated reset signal, storing the output of the adding step, and feeding back the stored value to the adding step as the preceding integral value; and  
       enabling according to the repeated reset signal, and storing a value from the adding step just before the storing step is reset.  
     
     
       12. The method according to  claim 10 , wherein the period of the repeated reset signal inputted to step (b) is shortened. 
     
     
       13. The method according to  claim 10 , wherein step (d) converts the output of step (c) into sign and magnitude information, decides a gain control direction according to the sign information, and decides a gain control amount according to the magnitude information. 
     
     
       14. The method according to  claim 13 , wherein step (d) decides the gain control amount by squaring the magnitude information.